The invention relates to a machine tool, in particular for the rotary machining of workpieces.
Machine tools of this type are known, the tool carrier and the workpiece carrier being movable relative to each other in these known machine tools as a result of the fact that they are mounted directly on one or more slides movable in a linear manner relative to the machine frame.
In order to obtain three-dimensional mobility of the tool carrier and the workpiece carrier relative to each other, it is necessary to arrange at least one of the two on a cross slide.
A cross slide of this type has the drawback that in this case substantial masses have to be moved.
The object of the invention is therefore to provide a machine tool in which the moved masses can be kept as low as possible.
This object is attained according to the invention by a machine tool, in particular for the rotary machining of workpieces, in that the machine tool comprises a machine frame, a tool carrier, a workpiece carrier and a parallel kinematic arrangement, which has three parallelogram guides connected in an articulated manner at one end to a receiving means for one of the carriers and at the other end to one of the slides and an N/C-controlled linear drive for each slide and by which the carrier arranged on the receiving means is movable relative to the machine frame in a three-dimensional movement space.
The advantage of the parallel kinematic arrangement according to the invention is that the moved masses can be kept low by means of this, since each slide has to be guided movably only in one axial direction and so all the drives for the slides can be arranged on the machine frame.
In principle it would be sufficient in the case of a machine tool according to the invention for the tool carrier to be equipped with one tool. It is particularly advantageous, however, if the tool carrier can be equipped with a plurality of tools, so that as extensive a complete machining as possible can be performed by the plurality of tools
In principle it would be possible in this case for the tools to be arranged along one direction, for example in a linear manner. It is particularly advantageous, however, for the machine tool according to the invention to be constructed when the plurality of tools are arranged in two directions and mutually spaced in each case, so that a two-dimensional matrix of tools is available.
By means of a two-dimensional matrix a plurality of tools can be arranged in a relatively small space, so that in this way the space requirement of the machine tool in particular is small despite the plurality of tools.
A particularly advantageous solution provides that the plurality of tools can be used for machining a workpiece, so that in this way a time-saving complete machining is made possible by a rapid change from machining with one tool to machining with the other tool.
In principle, in the case of the machine tool according to the invention it would be possible to provide a tool carrier in which the tools are movable relative to the machine frame. A known tool carrier of this type is a tool revolver, which may be a revolver rotatable about a revolver axis or even a linear revolver.
It is particularly advantageous for the solution according to the invention, however, in particular on account of the existing three-dimensional mobility of the receiving means, if the tool carrier is arranged stationary on the machine frame and, in particular, the tools used are arranged with such an orientation that they can be used for machining by bringing the workpiece to the tool, so that in this case exclusively the workpiece carrier is movable relative to the machine frame by means of the receiving means.
In order to ensure an optimum chip clearance it is preferably provided that chip spaces, by way of which the chips produced can be removed, are arranged between the tools.
It is particularly advantageous in this case if the tool carrier has an aperture for the removal of chips which drop down, so that these chips can be removed in a simple manner.
In this case a particularly expedient arrangement in the case of a plurality of tools provides that the tools are arranged around the aperture.
In addition, in order to obtain an expedient removal of the chips by way of the machine frame, it is preferably provided that the tool carrier is arranged in the machine frame above a recess which receives falling chips.
With respect to the arrangement of the receiving means relative to the parallel kinematic arrangement used according to the invention, more precise details have not been provided hitherto. For example, the parallel kinematic arrangement could be designed in such a way that the receiving means is supported by the parallel kinematic arrangement with respect to the machine frame, i.e. the receiving means stresses the parallelogram guides essentially with pressure.
In the case of a workpiece receiving means with a tool arranged in a suspended manner, however, this would have the disadvantage that in this case the parallelogram guides would extend on the same side as the workpiece and would restrict the operating space.
For this reason a particularly advantageous embodiment provides that the receiving means is arranged in a suspended manner on the parallelogram guides and so the latter are stressed by tension. The parallelogram guides are thus situated in a region in which they do not restrict the accessibility to the operating space and also not the operating space itself.
With respect to the workpiece receiving means it would be possible to arrange them in such a way that the workpiece rests thereon. It is particularly expedient, however, if the workpiece receiving means receives the workpiece in a suspended manner.
With respect to the design of the workpiece receiving means, no more precise details have been given in conjunction with the previous explanation of the individual embodiments. In this way, it would be possible, for example, to use a driven tool for machining a workpiece, so that it would be sufficient to use the workpiece carrier only for positioning the workpiece relative to the driven tool.
A particularly advantageous solution, however, in particular with respect to rotary machining, provides that the workpiece carrier is a workpiece spindle.
For example, in the case of the solution according to the invention the workpiece spindle could be arranged as before on the machine frame and the workpiece could be machinable by arranging the workpiece carrier on the receiving means.
It is particularly expedient, however, particularly in order to be able to integrate a workpiece manipulation in a simple manner without additional manipulation devices, if the workpiece spindle is arranged on the receiving means, so that the workpiece spindle is movable in the movement space provided for the receiving means.
To this end, it is preferably provided that the workpiece spindle is movable in the movement space in such a way that all the tools of the tool carrier can be used on the workpiece.
In this case the workpiece spindle is advantageously designed in the form of a suspended spindle, i.e. the workpiece spindle is arranged on the receiving means in such a way that the workpiece receiving means points in the direction of a base area of the machine tool.
It is particularly expedient if the workpiece spindle is a vertical spindle, i.e. the spindle axis is designed in such a way that it extends substantially parallel to the vertical. With a vertical spindle of this type, gripping and/or depositing a workpiece can advantageously be combined with machining, particularly in the case of small parts. In this way, for example, in particular the three-dimensional mobility of the workpiece spindle can be utilized expediently in order to grip and/or to machine a workpiece available on a conveying device and subsequently to deposit it again.
In addition to the movable workpiece spindle, however, the concept according to the invention can also advantageously provide a counter spindle which is arranged adjacent to the tools on the machine frame.
In this case, either tools arranged separately should then be provided which can be arranged fixed on the machine frame for example, provided that the counter spindle is movable, or it is possible to provide tools on the receiving means for example for the workpiece spindle at the same time, so that machining is possible when the counter spindle is stationary.
With respect to the design of the machine frame itself, no more precise details have been given in conjunction with the previous explanation of the individual embodiments. In this way, a particularly advantageous embodiment provides that the machine frame comprises a base body which can be placed on a setting area and supports projecting therefrom for the linear drives.
In this case all the supports preferably extend parallel to one another away from the base body.
A particularly expedient embodiment of the solution according to the invention provides that the base body has a substantially triangular cross-sectional shape in a horizontal cross-sectional plane, and a carrier is arranged in each corner region.
In this case it is particularly expedient if the base body has substantially the cross-sectional shape of an isosceles [sic] triangle in the horizontal cross-sectional plane, so that the carriers are arranged at substantially equal angular distances about a median axis.
A particularly stable solution for the machine frame is provided when the carriers projecting from the base body are connected to one another by means of a cross-bracing member on their side remote from the base body, thus additionally resulting in stabilization of the carriers relative to one another.
By means of a cross-bracing member of this type, a sort of cage structurexe2x80x94in which the carriers are integratedxe2x80x94is formed in conjunction with the base body.
To this end an alternative solution provides that the carriers are stabilized with respect to the base body by wall members. Such a solution, however, has the drawback of restricted accessibility as compared with the cage structure of the machine frame according to the invention.
In this case a particularly expedient solution provides that the carriers are connected to one another by a one-piece cross-bracing member on their side remote from the base body.
With respect to the movement path of the slide, no more precise details have like-wise been given in conjunction with the previous explanation of the individual embodiments. In this way, a particularly advantageous embodiment provides that a movement path of the slides extends between the base body and the cross-bracing member.
In this case, as large a slide path as possible is made available in order to obtain as large a movement space as possible for the movement of the receiving means.
In order to protect the slide guide and the linear drive from chips, it is preferably provided that the respective linear drive is protected by a dimensionally rigid covering which is jointly moved with the respective slide in a rigid manner.
In this case it is particularly advantageous if in all positions of the slide the covering extends at least from the slide as far as the base body and so the region of the linear drive situated to a pronounced extent in the chip clearance is protected to an optimum degree.
Since according to the invention the covering is to be jointly movable with the slide in a rigid manner and thus should not be changeable in shape itself, it has to have a length which substantially corresponds to the maximum path of travel of the slide. For this reason it is advantageously provided that the covering enters a covering-receiving means.
A covering-receiving means of this type could for example be a covering member additionally provided on the base body for example.
A solution which is particularly expedient in terms of simplicity provides, however, that the covering enters a recess provided in the base body for it.
In this case the recess is preferably dimensioned in such a way that only a slight gap remains between it and the covering, so that the gap is already sufficient to prevent the penetration of further chips.
It is also provided within the scope of the invention, however, that a wiping means is provided between the covering and an entry opening of the recess for the covering.
In order to ensure that chips are removed, even in the case where these chips enter the recess, it is preferably provided that the recess in the base body is open on the side opposite the entrance for the covering, so that it is possible for the chips and/or fluid from the recess to pass out again on the side opposite the entrance to the covering.
In addition, an advantageous embodiment of the solution according to the invention provides that one respective dimensionally rigid coveringxe2x80x94moved jointly with the slidexe2x80x94for the linear drive extends between the respective slide and a closure of the operating space opposite the base body. In this way, this part of the linear drive can also be protected in an advantageous manner.
In this case it is preferably provided that in all positions of the slide the covering extends at least as far as the wall of the operating space opposite the base body.
The covering can be arranged in a particularly simple and expedient manner relative to the slide if it directly adjoins a housing of the slide and is held thereon.
In conjunction with the previous description of individual embodiments of the solution according to the invention, no more precise details are given as to how a line train is to be guided to the receiving means which is movable by the parallel kinematic arrangement, in particular since this line train has to be guided in the operating space in which the receiving means moves with the carrier held thereon.
In this way, it is particularly advantageous if a line train to the receiving means movable by the parallel kinematic arrangement is guided by a line-train protection movable with respect to the carrier held on the receiving means and the machine frame.
A line-train protection of this type is used to protect the line train from any type of damage from chips flying about in the operating space and lubricant and coolant splashing in the operating space.
In this case it is particularly advantageous if the line-train protection comprises a tube which is mounted in a pivot bearing mounted on the machine frame so as to be displaceable in its longitudinal direction.
This means that the tube is pivotable with respect to the machine frame on account of the pivot bearing on the one hand and is also mounted displaceably in the pivot bearing in its longitudinal direction relative to the pivot bearing on the other hand, so that, starting from the pivot bearing, the tube can extend by a different length in the operating space.
In this case a particularly expedient solution provides that the tube is mounted in a pivotable manner by means of the pivot bearing on the wall of the operating space opposite the base body and passes through the said wall.
Widely different solutions are possible with respect to the design of the pivot bearing. A particularly simple and inexpensive solution provides that the pivot bearing comprises a pivot member for receiving the tube, which [pivot bearing] is mounted in an articulated manner in a pivot-member bearing mounted stationary on the machine frame.
In this case the pivot member is preferably designed in such a way that it has a spherical face and is mounted therewith in the pivot-member bearing.
A spherical face of this type has the advantage that it ensures an optimum pivotability on the one hand and it also has the advantage that it also allows rotation about the tube itself on the other hand.
In addition it is also advantageously provided that the tube is also mounted in the pivot member so as to be rotatable about its longitudinal axis, so that relative rotation can be compensated by these mountings alone.
With respect to the design of the parallelogram guides, no more precise details have been given in conjunction with the previous description of the individual embodiments. In this way, a particularly advantageous embodiment provides that the parallelogram guides comprise two parallelogram braces extending constantly parallel to each other in all the positions of the receiving means in the operating space. As a result of such parallelogram braces which extend constantly parallel to each other, an advantageous stabilization of the position of the receiving means in the operating space is achieved.
In order to protect the articulated connexion between the parallelogram braces and the receiving means from the ingress of chips and the ingress of coolant and/or lubricant on account of their position which is relatively close in the case of the workpiece, it is preferably provided that the parallelogram braces are held on the receiving means by means of a joint situated below a protection device.
In this case the protection device is preferably designed in such a way that it comprises a covering member which is connected to a guiding head on the respective parallelogram braces in a movable manner.
In order to guide the covering member precisely, it is preferably provided that the covering member is movable on a guiding face in order to follow the movements of the guiding head when the parallelogram brace is moved.
In order to provide a dirt-tight connexion between the covering member and the respective parallelogram brace, it is preferably provided that in all positions of the parallelogram brace the covering member rests against the guiding head with a guiding lug relative to the receiving means, a guiding lug of this type being formed as an aperture in the covering member in the simplest case.
In this case a particularly preferred solution provides that the guiding head has a shape which in each position of the covering member determined by the guiding face has a bearing contour with substantially the same shape for the guiding lug, so that in all positions of the respective parallelogram brace the guiding lug can rest against the guiding head in a manner closing it off tightly.
A particularly advantageous embodiment provides that the joints between the parallelogram braces and the slide are also protected by a suitable protection device.